Vial bottles in which a powdered drug is enclosed in an airtight manner are widely available. When such a drug is given to a patient, a solvent is injected into a vial bottle to dissolve the drug so that a drug solution can be obtained, and then the drug solution is transferred from the vial bottle to a drug solution bag. To inject a solvent into a vial bottle or take a drug solution out of a vial bottle, a plug member (a rubber plug) that seals the mouth (the opening) of the vial bottle is pierced with a puncture needle (also referred to as “a bottle needle”).
A drug that is enclosed in a vial bottle may be a drug specified as a powerful drug such as an anticancer drug. It is necessary to avoid situations in which such a dangerous drug or a solution thereof adheres to a worker's finger or the like, and situations in which a worker breathes in the drug or vapor therefrom. Therefore, in order to prevent a puncture needle that pierces through a plug member of a vial bottle from unintentionally coming out of the plug member, an adapter in which claws, which engage with a flange that has an expanded diameter and surrounds the mouth of a vial bottle (or an aluminum cap that covers the flange), are provided integrally with a puncture needle is often used.
Patent Document 1 discloses an example of such an adapter. In an adapter 900 according to Patent Document 1, as shown in FIG. 12, claws 930 that protrude toward a puncture needle 910 are provided at leading end portions of arms 920 that face the puncture needle 910. The arms 920 are elastically bendable so that the claws 930 can be displaced in radial directions so as to move away (outward) from the puncture needle 910. Upon the adapter 900 being pressed toward the plug member of the vial bottle, the puncture needle 910 starts piercing the plug member, and, in tandem with that, slidable portions 933a of the claws 930 abut against an edge of an aluminum cap of the vial bottle. The slidable portions 933a slide on the aluminum cap as the puncture needle 910 enters into the plug member. Since the slidable portions 933a are inclined, the claws 930 are displaced outward away from the puncture needle 910 while the slidable portions 933a slide on the aluminum cap. Upon the claws 930 having moved past the aluminum cap, the arms 920 elastically return to their original shape, and the claws 930 engage with the flange. In this way, it is possible to pierce the plug member with the puncture needle 910 and engage the claws 930 with the flange by simply pressing the adapter 900 toward the vial bottle.